The present invention relates to the manufacture of smokable materials, and in particular, to the processing of tobacco products using extrusion technology.
Cigarettes are popular smoking articles which have a substantially cylindrical rod shaped structure and include a charge of tobacco material surrounded by a wrapper such as paper thereby forming a so-called "tobacco rod." It has become desirable to manufacture cigarettes having cylindrical filters aligned in an end-to-end relationship with the tobacco rod. Typically, filters are manufactured from fibrous materials such as cellulose acetate, and are attached to the tobacco rod using a circumscribing tipping material. Cigarettes often can include processed, reconstituted or reclaimed tobacco materials. Although numerous methods for processing, reconstituting or reclaiming tobacco materials are known, there has been interest in providing such materials using various extrusion techniques.
Numerous references address methods for providing extruded smokable materials. For example, U.S. Pat. No. 3,203,432 to Green et al proposes grinding tobacco to a small size, mixing the tobacco with water, and extruding the mixture into filamentary form. U.S. Pat. No. 4,598,721 to Stiller et al proposes producing crimped fiber pieces from tobacco waste using an extruder having a die head for producing filiform products and a rotating blade at the die head. U.S. Pat. No. 3,932,081 to Buchmann et al proposes extruding smokable fibers from a suspension of ground tobacco. U.S. Pat. No. 4,347,855 to Lanzillotti et al and U.S. Pat. No. 4,391,285 to Burnett et al propose extruding smoking articles having highly specific shapes and configurations as well as controlled porosities and densities. U.S. Pat. Nos. 4,510,950 and 4,625,737 to Keritsis et al propose providing foamed, extruded tobacco-containing smoking articles.
Although various methods for physically processing smokable materials exist, there does not appear to be known any specific manners or methods for providing controlled and significant composition changes to the tobacco material during extrusion. In order to efficiently and effectively provide smokable material of unique, improved or controlled smoking character or composition, it would be desirable to employ a method for significantly changing the chemical composition of tobacco material during an extrusion process.